Monica Aasrum

• Amrutkar, Manoj; Berg, Kjersti; Balto, Aina; Skilbrei, Miguel Garcia; Finstadsveen, Anette Vefferstad & Aasrum, Monica [Show all 8 contributors for this article] (2023). Pancreatic stellate cell-induced gemcitabine resistance in pancreatic cancer is associated with LDHA- and MCT4-mediated enhanced glycolysis. Cancer Cell International. 23, p. 1–17. doi: 10.1186/s12935-023-02852-7. Full text in Research Archive Show summary

  Background Profound resistance to chemotherapy remains a major challenge in achieving better clinical outcomes for patients with pancreatic ductal adenocarcinoma (PDAC). Recent studies indicate that gemcitabine (GEM) resistance is promoted both by pancreatic stellate cells (PSCs) and through increased glycolysis. However, it remains unknown whether PSCs affect GEM sensitivity via glycolytic regulation. Methods Human pancreatic cancer cell (PCC) lines (BxPC-3, Capan-2, HPAF-II, Mia PaCa-2, Panc-1, SW-1990) were exposed to three different PSC-conditioned media (PSC-CM; PSC-1, PSC-2, HPaSteC), following either pre-treatment with glycolysis inhibitor NV-5440 or transfection for transient silencing of key glycolytic regulators (LDHA and MCT4). Proliferation, glucose transport, extracellular lactate, and GEM sensitivity were assessed. Protein expression was determined by Western blot and immunostaining. Moreover, secreted proteins in PSC-CMs were profiled by mass spectrometry (MS). Results While exposure to PSC-CMs did not affect glucose transport in PCCs, it increased their lactate release and proliferation, and reduced the sensitivity for GEM. Both NV-5440 treatment and transient silencing of LDHA and MCT4 inhibited these PSC-induced changes in PCCs. MS analysis identified 688 unique proteins with differential expression, of which only 87 were common to the three PSC-CMs. Most PSC-secreted proteins were extracellular matrix-related, including SPARC, fibronectin, and collagens. Moreover, exposure to PSC-CMs increased the phosphorylation of ERK in PCCs, but the treatment of PCCs with the MEK/ERK inhibitor PD98059 resulted in a reduction of PSC-CM-induced glycolysis and improved GEM sensitivity. Conclusions The study findings suggest that PSC-secreted factors promote both glycolysis and GEM resistance in PCCs, and that glycolysis inhibition by NV-5440 and blocking of ERK phosphorylation by PD98059 protect PCCs from PSC-CM-induced loss of GEM sensitivity. Taken together, PSCs appear to promote GEM resistance in PDAC via glycolysis. Thus, targeting glycolysis may improve the effect of chemotherapy in PDAC.

• Manfra, Ornella; Calamera, Gaia; Froese, Alexander; Arunthavarajah, Dulasi; Surdo, Nicoletta C. & Meier, Silja [Show all 14 contributors for this article] (2022). CNP regulates cardiac contractility and increases cGMP near both SERCA and TnI: difference from BNP visualized by targeted cGMP biosensors. Cardiovascular Research (CVR). ISSN 0008-6363. 118(6), p. 1506–1519. doi: 10.1093/cvr/cvab167. Full text in Research Archive Show summary

  Abstract Aims Guanylyl cyclase-B (GC-B; natriuretic peptide receptor-B, NPR-B) stimulation by C-type natriuretic peptide (CNP) increases cGMP and causes a lusitropic and negative inotropic response in adult myocardium. These effects are not mimicked by NPR-A (GC-A) stimulation by brain natriuretic peptide (BNP), despite similar cGMP increase. More refined methods are needed to better understand the mechanisms of the differential cGMP signalling and compartmentation. The aim of this work was to measure cGMP near proteins involved in regulating contractility to understand compartmentation of cGMP signalling in adult cardiomyocytes. Methods and results We constructed several fluorescence resonance energy transfer (FRET)-based biosensors for cGMP subcellularly targeted to phospholamban (PLB) and troponin I (TnI). CNP stimulation of adult rat cardiomyocytes increased cGMP near PLB and TnI, whereas BNP stimulation increased cGMP near PLB, but not TnI. The phosphodiesterases PDE2 and PDE3 constrained cGMP in both compartments. Local receptor stimulation aided by scanning ion conductance microscopy (SICM) combined with FRET revealed that CNP stimulation both in the t-tubules and on the cell crest increases cGMP similarly near both TnI and PLB. In ventricular strips, CNP stimulation, but not BNP, induced a lusitropic response, enhanced by inhibition of either PDE2 or PDE3, and a negative inotropic response. In cardiomyocytes from heart failure rats, CNP increased cGMP near PLB and TnI more pronounced than in cells from sham-operated animals. Conclusion These targeted biosensors demonstrate that CNP, but not BNP, increases cGMP near TnI in addition to PLB, explaining how CNP, but not BNP, is able to induce lusitropic and negative inotropic responses.

• Amrutkar, Manoj; Vethe, Nils Tore; Verbeke, Caroline Sophie; Aasrum, Monica; Vefferstad, Anette & Santha, Petra [Show all 7 contributors for this article] (2020). Differential gemcitabine sensitivity in primary human pancreatic cancer cells and paired stellate cells is driven by heterogenous drug uptake and processing. Cancers. 12:3628(12), p. 1–18. doi: 10.3390/cancers12123628. Full text in Research Archive Show summary

  Gemcitabine resistance in pancreatic ductal adenocarcinoma (PDAC) is attributed to cancer cell-intrinsic drug processing and the impact of the tumor microenvironment, especially pancreatic stellate cells (PSCs). This study uses human PDAC-derived paired primary cancer cells (PCCs) and PSCs from four different tumors, and the PDAC cell lines BxPC-3, Mia PaCa-2, and Panc-1, to assess the fate of gemcitabine by measuring its cellular uptake, cytotoxicity, and LC-MS/MS-based metabolite analysis. Expression analysis and siRNA-mediated knockdown of key regulators of gemcitabine (hENT1, CDA, DCK, NT5C1A) was performed. Compared to PSCs, both the paired primary PCCs and cancer cell lines showed gemcitabine-induced dose-dependent cytotoxicity, high uptake, as well as high and variable intracellular levels of gemcitabine metabolites. PSCs were gemcitabine-resistant and demonstrated significantly lower drug uptake, which was not influenced by co-culturing with their paired PCCs. Expression of key gemcitabine regulators was variable, but overall strong in the cancer cells and significantly lower or undetectable in PSCs. In cancer cells, hENT1 inhibition significantly downregulated gemcitabine uptake and cytotoxicity, whereas DCK knockdown reduced cytotoxicity. In conclusion, heterogeneity in gemcitabine processing among different pancreatic cancer cells and stellate cells results from the differential expression of molecular regulators which determines the effect of gemcitabine.

• Amrutkar, Manoj; Larsen, Emma Kristine; Aasrum, Monica; Finstadsveen, Anette Vefferstad; Andresen, Per Arne & Verbeke, Caroline Sophie [Show all 7 contributors for this article] (2020). Establishment and Characterization of Paired Primary Cultures of Human Pancreatic Cancer Cells and Stellate Cells Derived from the Same Tumor. Cells. 9:227(1), p. 1–18. doi: 10.3390/cells9010227. Full text in Research Archive Show summary

  Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely poor prognosis, and its treatment remains a challenge. As the existing in vitro experimental models offer only a limited resemblance to human PDAC, there is a strong need for additional research tools to better understand PDAC tumor biology, particularly the impact of the tumor stroma. Here, we report for the first time the establishment and characterization of human PDAC-derived paired primary monolayer cultures of (epithelial) cancer cells (PCCs) and mesenchymal stellate cells (PSCs) derived from the same tumor by the outgrowth method. Characterization of cell morphology, cytostructural, and functional profiles and proteomics-based secretome analysis were performed. All PCCs harbored KRAS and TP53 mutations, and expressed cytokeratin 19, ki-67, and p53, while the expression of EpCAM and vimentin was variable. All PSCs expressed α-smooth muscle actin (α-SMA) and vimentin. PCCs showed a significantly higher growth rate and proliferation than PSCs. Secretome analysis confirmed the distinct nature of PCCs as compared to PSCs and allowed identification of potential molecular regulators of PSC-conditioned medium (PSC-CM)-induced migration of PCCs. Paired primary cultures of PCCs and PSCs derived from the same tumor specimen represent a novel experimental model for basic research in PDAC tumor biology.

• Amrutkar, Manoj; Aasrum, Monica; Verbeke, Caroline Sophie & Gladhaug, Ivar Prydz (2019). Secretion of fibronectin by human pancreatic stellate cells promotes chemoresistance to gemcitabine in pancreatic cancer cells. BMC Cancer. 19(596). doi: 10.1186/s12885-019-5803-1. Full text in Research Archive Show summary

  Background Gemcitabine remains a cornerstone in chemotherapy of pancreatic ductal adenocarcinoma (PDAC) despite suboptimal clinical effects that are partly due to the development of chemoresistance. Pancreatic stellate cells (PSCs) of the tumor stroma are known to interact with pancreatic cancer cells (PCCs) and influence the progression of PDAC through a complex network of signaling molecules that involve extracellular matrix (ECM) proteins. To understand tumor-stroma interactions regulating chemosensitivity, the role of PSC-secreted fibronectin (FN) in the development of gemcitabine resistance in PDAC was examined. Methods PSC cultures obtained from ten different human PDAC tumors were co-cultured with PCC lines (AsPC-1, BxPC-3, Capan-2, HPAF-II, MIA PaCa-2, PANC-1 and SW-1990) either directly, or indirectly via incubation with PSC-conditioned medium (PSC-CM). Gemcitabine dose response cytotoxicity was determined using MTT based cell viability assays. Protein expression was assessed by western blotting and immunofluorescence. PSC-CM secretome analysis was performed by proteomics-based LC-MS/MS, and FN content in PSC-CM was determined with ELISA. Radiolabeled gemcitabine was used to determine the capacity of PCCs to uptake the drug. Results In both direct and indirect co-culture, PSCs induced varying degrees of resistance to the cytotoxic effects of gemcitabine among all cancer cell lines examined. A variable degree of increased phosphorylation of ERK1/2 was observed across all PCC lines upon incubation with PSC-CM, while activation of AKT was not detected. Secretome analysis of PSC-CM identified 796 different proteins, including several ECM-related proteins such as FN and collagens. Soluble FN content in PSC-CM was detected in the range 175–350 ng/ml. Neither FN nor PSC-CM showed any effect on PCC uptake capacity of gemcitabine. PCCs grown on FN-coated surface displayed higher resistance to gemcitabine compared to cells grown on non-coated surface. Furthermore, a FN inhibitor, synthetic Arg-Gly-Asp-Ser (RGDS) peptide significantly inhibited PSC-CM-induced chemoresistance in PCCs via downregulation of ERK1/2 phosphorylation. Conclusions The findings of this study suggest that FN secreted by PSCs in the ECM plays a key role in the development of resistance to gemcitabine via activation of ERK1/2. FN-blocking agents added to gemcitabine-based chemotherapy might counteract chemoresistance in PDAC and provide better clinical outcomes.

• Lenggenhager, Daniela; Amrutkar, Manoj; Santha, Petra; Aasrum, Monica; Löhr, Johannes-Matthias & Gladhaug, Ivar Prydz [Show all 7 contributors for this article] (2019). Commonly Used Pancreatic Stellate Cell Cultures Differ Phenotypically and in Their Interactions With Pancreatic Cancer Cells. Cells. 8:E23(1), p. 1–18. doi: 10.3390/cells8010023. Full text in Research Archive Show summary

  Activated pancreatic stellate cells (PSCs) play a central role in the tumor stroma of pancreatic ductal adenocarcinoma (PDAC). Given the limited availability of patient-derived PSCs from PDAC, immortalized PSC cell lines of murine and human origin have been established; however, it is not elucidated whether differences in species, organ disease status, donor age, and immortalization alter the PSC phenotype and behavior compared to that of patient-derived primary PSC cultures. Therefore, a panel of commonly used PSC cultures was examined for important phenotypical and functional features: three primary cultures from human PDAC, one primary from normal human pancreas, and three immortalized (one from human, two from murine pancreas). Growth rate was considerably lower in primary PSCs from human PDAC. Basal collagen synthesis varied between the PSC cultures, and TGF-β stimulation increased collagen synthesis only in non-immortalized cultures. Differences in secretome composition were observed along with a divergence in the DNA synthesis, migration, and response to gemcitabine of PDAC cell lines that were grown in conditioned medium from the various PSC cultures. The findings reveal considerable differences in features and functions that are key to PSCs and in the interactions with PDAC. These observations may be relevant to researchers when selecting the most appropriate PSC culture for their experiments.

• Aasrum, Monica; Thoresen, G. Hege; Christoffersen, Thoralf & Brusevold, Ingvild Johnsen (2018). p38 differentially regulates ERK, p21, and mitogenic signalling in two pancreatic carcinoma cell lines. Journal of cell communication and signaling. ISSN 1873-9601. 12(4), p. 699–707. doi: 10.1007/s12079-017-0444-0. Full text in Research Archive Show summary

  Whereas the p38 MAP kinase has largely been associated with anti-proliferative functions, several observations have indicated that it may also have positive effects on proliferation. In hepatocytes, we have found that p38 has opposing effects on DNA synthesis when activated by EGF and HGF. Here we have studied the function of p38 in EGF- and HGF-induced DNA synthesis in the two pancreatic carcinoma cell lines AsPC-1 and Panc-1. In Panc-1 cells, the MEK inhibitor PD98059 reduced EGF- and HGF-induced DNA synthesis, while the p38 inhibitor SB203580 strongly increased the basal DNA synthesis and reduced expression of the cyclin-dependent kinase inhibitor (CDKI) p21. In contrast, in AsPC-1 cells, EGF- and HGF-induced DNA synthesis was not significantly reduced by PD98059 but was inhibited by SB203580. Treatment with SB203580 amplified the sustained ERK phosphorylation induced by these growth factors and caused a marked upregulation of the expression of p21, which could be blocked by PD98059. These results suggest that while DNA synthesis in Panc-1 cells is enhanced by ERK and strongly suppressed by p38, in AsPC-1 cells, p38 exerts a pro-mitogenic effect through MEK/ERK-dependent downregulation of p21. Thus, p38 may have suppressive or stimulatory effects on proliferation depending on the cell type, due to differential cross-talk between the p38 and MEK/ERK pathways.

• Tjomsland, Vegard; Aasrum, Monica; Christoffersen, Thoralf & Gladhaug, Ivar Prydz (2017). Functional heterogeneity in tumor-derived human pancreatic stellate cells: Differential expression of HGF and implications for mitogenic signaling and migration in pancreatic cancer cells. OncoTarget. 8(42), p. 71672–71684. doi: 10.18632/oncotarget.17800. Full text in Research Archive
• Ødegård, John; Sondresen, Jan Erik; Aasrum, Monica; Tveteraas, Ingun Heiene; Guren, Tormod Kyrre & Christoffersen, Thoralf [Show all 7 contributors for this article] (2017). Differential effects of epidermal growth factor (EGF) receptor ligands on receptor binding, downstream signalling pathways and DNA synthesis in hepatocytes. Growth Factors. ISSN 0897-7194. 35(6), p. 239–248. doi: 10.1080/08977194.2018.1453506. Full text in Research Archive
• Aasrum, Monica; Brusevold, Ingvild Johnsen; Christoffersen, Thoralf & Thoresen, G. Hege (2016). HGF-induced DNA synthesis in hepatocytes is suppressed by p38. Growth Factors. ISSN 0897-7194. 34(5-6), p. 217–223. doi: 10.1080/08977194.2017.1285765. Full text in Research Archive
• Tveteraas, Ingun Heiene; Aasrum, Monica; Brusevold, Ingvild Johnsen; Ødegård, John; Christoffersen, Thoralf & Sandnes, Dagny Lise (2016). Lysophosphatidic acid induces both EGFR-dependent and EGFR-independent effects on DNA synthesis and migration in pancreatic and colorectal carcinoma cells. Tumour Biology. ISSN 1010-4283. 37(2), p. 2519–2526. doi: 10.1007/s13277-015-4010-1. Full text in Research Archive
• Tjomsland, Vegard; Pomianowska, Ewa; Aasrum, Monica; Sandnes, Dagny Lise; Verbeke, Caroline Sophie & Gladhaug, Ivar Prydz (2016). Profile of MMP and TIMP expression in human pancreatic stellate cells: regulation by IL-1? and TGF? and implications for migration of pancreatic cancer cells. Neoplasia. ISSN 1522-8002. 18(7), p. 447–456. doi: 10.1016/j.neo.2016.06.003. Full text in Research Archive
• Aasrum, Monica; Tjomsland, Vegard; Thoresen, G. Hege; Angelis, Paula De; Christoffersen, Thoralf & Brusevold, Ingvild Johnsen (2016). PI3K is required for both basal and LPA-induced DNA synthesis in oral carcinoma cells. Journal of Oral Pathology & Medicine. ISSN 0904-2512. 45(6), p. 425–432. doi: 10.1111/jop.12384. Full text in Research Archive
• Tjomsland, Vegard; Sandnes, Dagny Lise; Pomianowska, Ewa; Cizmovic, Smiljana Torbica; Aasrum, Monica & Brusevold, Ingvild Johnsen [Show all 8 contributors for this article] (2016). The TGFβ-SMAD3 pathway inhibits IL-1α induced interactions between human pancreatic stellate cells and pancreatic carcinoma cells and restricts cancer cell migration. Journal of Experimental & Clinical Cancer Research. 35:122, p. 1–12. doi: 10.1186/s13046-016-0400-5. Full text in Research Archive Show summary

  Background The most abundant cells in the extensive desmoplastic stroma of pancreatic adenocarcinomas are the pancreatic stellate cells, which interact with the carcinoma cells and strongly influence the progression of the cancer. Tumor stroma interactions induced by IL-1α/IL-1R1 signaling have been shown to be involved in pancreatic cancer cell migration. TGFβ and its receptors are overexpressed in pancreatic adenocarcinomas. We aimed at exploring TGFβ and IL-1α signaling and cross-talk in the stellate cell cancer cell interactions regulating pancreatic adenocarcinoma cell migration. Methods Human pancreatic stellate cells were isolated from surgically resected pancreatic adenocarcinomas and cultured in the presence of TGFβ or pancreatic adenocarcinoma cell lines. The effects of TGFβ were blocked by inhibitors or amplified by silencing the endogenous inhibitor of SMAD signaling, SMAD7. Pancreatic stellate cell responses to IL-1α or to IL-1α-expressing pancreatic adenocarcinoma cells (BxPC-3) were characterized by their ability to stimulate migration of cancer cells in a 2D migration model. Results In pancreatic stellate cells, IL-1R1 expression was found to be down-regulated by TGFβ and blocking of TGFβ signaling re-established the expression. Endogenous inhibition of TGFβ signaling by SMAD7 was found to correlate with the levels of IL-1R1, indicating a regulatory role of SMAD7 in IL-1R1 expression. Pancreatic stellate cells cultured in the presence of IL-1α or in co-cultures with BxPC-3 cells enhanced the migration of cancer cells. This effect was blocked after treatment of the pancreatic stellate cells with TGFβ. Silencing of stellate cell expression of SMAD7 was found to suppress the levels of IL-1R1 and reduce the stimulatory effects of IL-1α, thus inhibiting the capacity of pancreatic stellate cells to induce cancer cell migration. Conclusions TGFβ signaling suppressed IL-1α mediated pancreatic stellate cell induced carcinoma cell migration. Depletion of SMAD7 upregulated the effects of TGFβ and reduced the expression of IL-1R1, leading to inhibition of IL-1α induced stellate cell enhancement of carcinoma cell migration. SMAD7 might represent a target for inhibition of IL-1α induced tumor stroma interactions.

• Aasrum, Monica; Ødegård, John; Thoresen, G. Hege; Brusevold, Ingvild Johnsen; Sandnes, Dagny Lise & Christoffersen, Thoralf (2015). Gab1 amplifies signaling in response to low-intensity stimulation by HGF. Cell Biology International. ISSN 1065-6995. 39(10), p. 1177–1184. doi: 10.1002/cbin.10511. Full text in Research Archive
• Brusevold, Ingvild Johnsen; Tveteraas, Ingun Heiene; Aasrum, Monica; Ødegård, John; Sandnes, Dagny Lise & Christoffersen, Thoralf (2014). Role of LPAR3, PKC and EGFR in LPA-induced cell migration in oral squamous carcinoma cells. BMC Cancer. 14(1). doi: 10.1186/1471-2407-14-432. Full text in Research Archive Show summary

  Background Oral squamous cell carcinoma is an aggressive neoplasm with serious morbidity and mortality, which typically spreads through local invasive growth. Lysophosphatidic acid (LPA) is involved in a number of biological processes, and may have a role in cancer cell migration and invasiveness. LPA is present in most tissues and can activate cells through six different LPA receptors (LPAR1-6). Although LPA is predominantly promigratory, some of the receptors may have antimigratory effects in certain cells. The signalling mechanisms of LPA are not fully understood, and in oral carcinoma cells the specific receptors and pathways involved in LPA-stimulated migration are unknown. Methods The oral carcinoma cell lines E10, SCC-9, and D2 were investigated. Cell migration was studied in a scratch wound assay, and invasion was demonstrated in organotypic three dimensional co-cultures. Protein and mRNA expression of LPA receptors was studied with Western blotting and qRT-PCR. Activation of signalling proteins was examined with Western blotting and isoelectric focusing, and signalling mechanisms were further explored using pharmacological agents and siRNA directed at specific receptors and pathways. Results LPA stimulated cell migration in the two oral carcinoma cell lines E10 and SCC-9, but was slightly inhibitory in D2. The receptor expression profile and the effects of specific pharmacological antagonist and agonists indicated that LPA-stimulated cell migration was mediated through LPAR3 in E10 and SCC-9. Furthermore, in both these cell lines, the stimulation by LPA was dependent on PKC activity. However, while LPA induced transactivation of EGFR and the stimulated migration was blocked by EGFR inhibitors in E10 cells, LPA did not induce EGFR transactivation in SCC-9 cells. In D2 cells, LPA induced EGFR transactivation, but this was associated with slowing of a very high inherent migration rate in these cells. Conclusion The results demonstrate LPA-stimulated migration in oral carcinoma cells through LPAR3, mediated further by PKC, which acts either in concert with or independently of EGFR transactivation.

• Pomianowska, Ewa; Sandnes, Dagny Lise; Grzyb, Krzysztof; Schjølberg, Aasa Rambæk; Aasrum, Monica & Tveteraas, Ingun Heiene [Show all 9 contributors for this article] (2014). Inhibitory effects of prostaglandin E<sub>2</sub> on collagen synthesis and cell proliferation in human stellate cells from pancreatic head adenocarcinoma. BMC Cancer. 14(1). doi: 10.1186/1471-2407-14-413. Full text in Research Archive
• Aasrum, Monica; Ødegård, John; Sandnes, Dagny Lise & Christoffersen, Thoralf (2013). The involvement of the docking protein Gab1 in mitogenic signalling induced by EGF and HGF in rat hepatocytes. Biochimica et Biophysica Acta. ISSN 0006-3002. 1833(12), p. 3286–3294. doi: 10.1016/j.bbamcr.2013.10.004. Full text in Research Archive
• Tveteraas, Ingun Heiene; Müller, Kristin Meisdalen; Aasrum, Monica; Ødegård, John; Dajani, Olav & Guren, Tormod Kyrre [Show all 8 contributors for this article] (2012). Mechanisms involved in PGE2-induced transactivation of the epidermal growth factor receptor in MH1C1 hepatocarcinoma cells. Journal of Experimental and Clinical Cancer Research. ISSN 0392-9078. 31, p. 72–72. doi: 10.1186/1756-9966-31-72. Full text in Research Archive Show summary

  Background It is important to understand the mechanisms by which the cells integrate signals from different receptors. Several lines of evidence implicate epidermal growth factor (EGF) receptor (EGFR) in the pathophysiology of hepatocarcinomas. Data also suggest a role of prostaglandins in some of these tumours, through their receptors of the G protein-coupled receptor (GPCR) family. In this study we have investigated mechanisms of interaction between signalling from prostaglandin receptors and EGFR in hepatocarcinoma cells. Methods The rat hepatocarcinoma cell line MH1C1 and normal rat hepatocytes in primary culture were stimulated with EGF or prostaglandin E2 (PGE2) and in some experiments also PGF2α. DNA synthesis was determined by incorporation of radiolabelled thymidine into DNA, phosphorylation of proteins in signalling pathways was assessed by Western blotting, mRNA expression of prostaglandin receptors was determined using qRT-PCR, accumulation of inositol phosphates was measured by incorporation of radiolabelled inositol, and cAMP was determined by radioimmunoassay. Results In the MH1C1 hepatocarcinoma cells, stimulation with PGE2 or PGF2α caused phosphorylation of the EGFR, Akt, and ERK, which could be blocked by the EGFR tyrosine kinase inhibitor gefitinib. This did not occur in primary hepatocytes. qRT-PCR revealed expression of EP1, EP4, and FP receptor mRNA in MH1C1 cells. PGE2 stimulated accumulation of inositol phosphates but not cAMP in these cells, suggesting signalling via PLCβ. While pretreatment with EP1 and EP4 receptor antagonists did not inhibit the effect of PGE2, pretreatment with an FP receptor antagonist blocked the phosphorylation of EGFR, Akt and ERK. Further studies suggested that the PGE2-induced signal was mediated via Ca2+ release and not PKC activation, and that it proceeded through Src and shedding of membrane-bound EGFR ligand precursors by proteinases of the ADAM family. Conclusion The results indicate that in MH1C1 cells, unlike normal hepatocytes, PGE2 activates the MEK/ERK and PI3K/Akt pathways by transactivation of the EGFR, thus diversifying the GPCR-mediated signal. The data also suggest that the underlying mechanisms in these cells involve FP receptors, PLCβ, Ca2+, Src, and proteinase-mediated release of membrane-associated EGFR ligand(s).

• Ødegård, John; Aasrum, Monica; Tveteraas, Ingun Heiene; Bharath, Suman Preet; Sandnes, Dagny Lise & Christoffersen, Thoralf (2012). Role of ErbB2 in the prostaglandin E-2-induced enhancement of the mitogenic response to epidermal growth factor in cultured hepatocytes. Biochemical and Biophysical Research Communications - BBRC. ISSN 0006-291X. 421(2), p. 255–260. doi: 10.1016/j.bbrc.2012.03.148. Full text in Research Archive
• Brusevold, Ingvild Johnsen; Aasrum, Monica; Bryne, Magne & Christoffersen, Thoralf (2012). Migration induced by epidermal and hepatocyte growth factors in oral squamous carcinoma cells in vitro: role of MEK/ERK, p38 and PI-3 kinase/Akt. Journal of Oral Pathology & Medicine. ISSN 0904-2512. 41(7), p. 547–558. doi: 10.1111/j.1600-0714.2012.01139.x. Full text in Research Archive
• Müller, Kristin Meisdalen; Tveteraas, Ingun Heiene; Aasrum, Monica; Ødegård, John; Dawood, Mona & Dajani, Olav [Show all 8 contributors for this article] (2011). Role of protein kinase C and epidermal growth factor receptor signalling in growth stimulation by neurotensin in colon carcinoma cells. BMC Cancer. 11. doi: 10.1186/1471-2407-11-421. Full text in Research Archive Show summary

  Background Neurotensin has been found to promote colon carcinogenesis in rats and mice, and proliferation of human colon carcinoma cell lines, but the mechanisms involved are not clear. We have examined signalling pathways activated by neurotensin in colorectal and pancreatic carcinoma cells. Methods Colon carcinoma cell lines HCT116 and HT29 and pancreatic adenocarcinoma cell line Panc-1 were cultured and stimulated with neurotensin or epidermal growth factor (EGF). DNA synthesis was determined by incorporation of radiolabelled thymidine into DNA. Levels and phosphorylation of proteins in signalling pathways were assessed by Western blotting. Results Neurotensin stimulated the phosphorylation of both extracellular signal-regulated kinase (ERK) and Akt in all three cell lines, but apparently did so through different pathways. In Panc-1 cells, neurotensin-induced phosphorylation of ERK, but not Akt, was dependent on protein kinase C (PKC), whereas an inhibitor of the β-isoform of phosphoinositide 3-kinase (PI3K), TGX221, abolished neurotensin-induced Akt phosphorylation in these cells, and there was no evidence of EGF receptor (EGFR) transactivation. In HT29 cells, in contrast, the EGFR tyrosine kinase inhibitor gefitinib blocked neurotensin-stimulated phosphorylation of both ERK and Akt, indicating transactivation of EGFR, independently of PKC. In HCT116 cells, neurotensin induced both a PKC-dependent phosphorylation of ERK and a metalloproteinase-mediated transactivation of EGFR that was associated with a gefitinib-sensitive phosphorylation of the downstream adaptor protein Shc. The activation of Akt was also inhibited by gefitinib, but only partly, suggesting a mechanism in addition to EGFR transactivation. Inhibition of PKC blocked neurotensin-induced DNA synthesis in HCT116 cells. Conclusions While acting predominantly through PKC in Panc-1 cells and via EGFR transactivation in HT29 cells, neurotensin used both these pathways in HCT116 cells. In these cells, neurotensin-induced activation of ERK and stimulation of DNA synthesis was PKC-dependent, whereas activation of the PI3K/Akt pathway was mediated by stimulation of metalloproteinases and subsequent transactivation of the EGFR. Thus, the data show that the signalling mechanisms mediating the effects of neurotensin involve multiple pathways and are cell-dependent.

• Dajani, Olav; Meisdalen, Kristin; Guren, Tormod Kyrre; Aasrum, Monica; Tveteraas, Ingun Heiene & Lilleby, Peggy [Show all 9 contributors for this article] (2008). Prostaglandin E2 upregulates EGF-stimulated signaling in mitogenic pathways involving Akt and ERK in hepatocytes. Journal of Cellular Physiology. ISSN 0021-9541. 214. doi: 10.1002/jcp.21205. Full text in Research Archive

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• Brusevold, Ingvild Johnsen; Aasrum, Monica; Bryne, Magne & Christoffersen, Thoralf (2011). Signalmekanismer som medierer EGF- og HGF-indusert migrasjon i orale plateepitelkarsinomceller in vitro. Full text in Research Archive
• Brusevold, Ingvild Johnsen; Aasrum, Monica; Tveteraas, Ingun Heiene; Bryne, Magne & Christoffersen, Thoralf (2011). Signalling Mechanisms Mediating EGF- and HGF-induced Migration in Carcinoma Cells in Vitro. Full text in Research Archive
• Ødegård, John; Aasrum, Monica; Bharath, Suman Preet; Tveteraas, Ingun Heiene; Sandnes, Dagny Lise & Christoffersen, Thoralf (2010). Prostaglandin E2 regulates ErbB2 and ErbB3 in hepatocytes. Full text in Research Archive
• Tveteraas, Ingun Heiene; Müller, Kristin Meisdalen; Dajani, Olav; Guren, Tormod Kyrre; Aasrum, Monica & Ødegård, John [Show all 8 contributors for this article] (2010). Mechanisms of prostaglandin E2-induced transactivation of the EGF receptor in MH1C1 hepatoma cells. Full text in Research Archive
• Sandnes, Dagny Lise; Müller, Kristin Meisdalen; Tveteraas, Ingun Heiene; Aasrum, Monica; Dawood, Mona & Dajani, Olav [Show all 7 contributors for this article] (2010). Protein kinase C and epidermal growth factor receptor signalling mediate growth stimulation by neurotensin in the colon carcinoma cell line HCT116. European Journal of Cancer. ISSN 0959-8049. 8(5), p. 166–166. Full text in Research Archive
• Ødegård, John; Aasrum, Monica; Bharath, Suman Preet; Tveteraas, Ingun Heiene; Sandnes, Dagny Lise & Christoffersen, Thoralf (2010). Prostaglandin E2 upregulates ErbB2 and enhances EGF-stimulated DNA synthesis in hepatocytes. European Journal of Cancer. ISSN 0959-8049. 8(5), p. 124–125. Full text in Research Archive
• Tveteraas, Ingun Heiene; Müller, Kristin Meisdalen; Dajani, Olav; Guren, Tormod Kyrre; Aasrum, Monica & Ødegård, John [Show all 8 contributors for this article] (2010). Mechanisms of prostaglandin E2-induced transactivation of the EGF receptor in MH1C1 hepatoma cells. European Journal of Cancer. ISSN 0959-8049. 8(5), p. 141–141. Full text in Research Archive

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